Network data storage is typically provided by an array of disk drives integrated with large semiconductor cache memory. A file server is used to interface the cached disk array to the network. The file server performs mapping of a network files to logical block addresses of storage in the cached disk array and move data between a network clients and the storage in the cached disk array. The file server use a network block services protocol in a configuration process in order to export to the network client logical volumes of the network-attached storage, which become local pseudo-disk instances. See, for example, Jiang et al., Patent Application Publication US 2004/0059822 A1 published Mar. 25, 2004, entitled “Network Block Services for Client Access of Network-Attached Storage in an IP Network,” incorporated herein by reference. Network clients typically use a network file system access protocol to access one or more file systems maintained by the file server.
In a data storage subsystem, the logical block addresses of storage are subdivided into a logical volumes. Each logical volume is mapped to the physical storage using a respective striping and redundancy scheme and is addressable by a file server independently of which physical volume is storing the logical volume. A sparse meta-volume is a thin provisioned logical volume used by a file system to store user data on one or more slice volumes. Each slice volume provisioned under the sparse meta-volume is mapped to a logical unit of storage.
The storage technology described above, in combination with a continuing increase in disk drive storage density, file server processing power, and network bandwidth at decreasing cost, has provided network clients with more than an adequate supply of network storage capacity at affordable prices. The vast amount of stored information on volumes is interfering with quick recovery of a sparse volume during failover or reset of a file server because time to mount or recover a volume increases linearly contributing significantly to the failover and boot latency. A File System could not be mounted unless all the slice volumes provisioned under the sparse meta-volume has been completely instantiated. Instantiation of a sparse meta-volume with a large number of slice volumes would take at least few seconds to instantiate. Mounting of a large number of sparse meta-volumes in turn would take at least few minutes. This creates high latency and low availability during failover or reset of a file server when a sparse volume needs to be recovered.
Additionally a volume can become inconsistent due to corruption. The clients of the file server have been denied access to the file system to which the inconsistent volume belongs. Reducing the time it takes to recover a sparse meta-volume would be advancement in the data storage computer-related arts. This is becoming increasingly important as the amount of information being handled and stored grows geometrically over short time periods and such environments add more file systems and data at a rapid pace.